The field of ionic liquids (ILs) is one of the ?hottest topics? with the number of publications still growing exponentially. This is due to the negligible vapour pressure, non-flammability, wide liquid, solubility and miscibility range of most ILs. ILs have been often described as ?designer solvents?, as properties of their ions can be changed to improve the suitability for a given process. The possibility of using IL mixtures has also been taken into account for variation of their properties, for instance, density or viscosity. After the pioneering suggestion that the use of IL mixtures is a way to decrease their melting points to room temperature, they were recently proposed as effective replacements for neat ILs in dye-sensitised solar cells, due to the improved transport processes. Based on acquired experience at ISIS on single ILs, we would now like to study their mixtures.